Solid neutrals. You can't miss with a pair of armchairs upholstered in natural linen and a light rug. Mixing patterns with the throw pillows brings a bit of interest to the room, but keeping them in the neutral range means they will all go effortlessly together.
Be honest about what is used in this room and make space for it. Do you craft while watching TV? Do the kids use the living room as their playroom? Stop the constant struggle to clean up these items and put them where they "belong". Instead, work in some permanent living room storage space for toys, crafts, games and so on. If you need to make room first, take out items that are not frequently used in the living room. Books that you want to keep but that no one is likely to read again anytime soon could go on shelves in a bedroom, for instance.
Natural tones. The fireplace mantel in this living room invites you to sit down and read awhile by the fire. The timber shelving unit ties in with shelving used elsewhere in the room – a nifty trick to prevent fireside storage that looks like it doesn't belong.